SL74HC640 - Octal 3-State Inverting Bus Transceiver
SL74HC640 Octal 3-State Inverting Bus Transceiver High-Performance Silicon-Gate CMOS The SL74HC640 is identical in pinout to the LS/ALS640.
The device inputs are compatible with standard CMOS outputs; with pullup resistors, they are compatible with LS/ALSTTL outputs.
The SL74HC640 is a 3 -state transceiver that is used for 2 -way asynchronous communication between data buses.
The device has an active-low Output Enable pin, which is used to place the I/O ports into high-impedance states.
The Dir